Current communication modules are usually a 3G (3rd Generation, the third generation mobile communication technology) module or a 4G (4th Generation, the fourth generation mobile communication technology) module, which are generally assembled in smart terminals, such as mobile phones, tablet computers, and the like. When a communication module is connected to an internal control system, connection to a network can be achieved. A size and interface mode of a 3G/4G module will directly affect a size and connection mode of a corresponding smart terminal which has been assembled with the 3G/4G module. In particular, portable smart terminals have high requirements for a size and interface of a 3G/4G module.
However, currently available 3G/4G modules usually adopt a Mini-PCIe (Mini Peripheral Component Interconnect Express) interface. A Mini-PCIe interface has a relatively large volume, and thus cannot meet requirements of current portable smart terminals. In addition, when in use, a 3G/4G module generally needs to be hot plugged in and unplugged from a Mini-PCIe connector in the terminal. In other words, a 3G/4G module is plugged into, and/or unplugged from, a corresponding terminal when the power is still on, which allows users to remove or replace the 3G/4G module without shutting down the system and without turning off the power. In such mode, only a simple action of plugging or unplugging is necessary for removing the 3G/4G module; while the system keeps running without interruption. Thereby, the system's capability for timely recovery from a disaster, as well as, the system's extendibility and flexibility, are improved.
However, during hot plugging and unplugging, current 3G/4G modules have the problems set forth below:
1. USB (Universal Serial BUS) interface data corruption. With respect to a design of a PCB (Printed Circuit Board) of current 3G/4G modules, lengths of all signal and data pins are the same, such as a length of USB data interface's D+ (positive data) pin and D− (negative data) pin and a length of a power supply pin are the same. In this regard, when the 3G/4G module is unplugged, USB communication and data transmissions are disconnected at the same time. While, at that same time, data may still be under transmission. Accordingly, an associated host system may not have enough time to save the data, which may result in partial data loss.
2. Power interface generating large instantaneous current. When a 3G/4G module is plugged in, a power supply voltage in a host system will be immediately applied to a power supply end of the 3G/4G module, so as to generate a large instantaneous current. The large current may burn some elements in the power module of the 3G/4G module, and further lead to malfunction or even crash of the system.